Pasta and baked beans with some herbs was one of my favourites or pasta with salad cream and sweetcorn.
I also used to work in a convenience store in the evening so anything that went out of date that night we could take home as long as we left a note for the boss. That's how I invented cheapskate stew - the cheapest pasta you can find, the cheapest tomato cupasoup you can find and all the veggies that got written off from work that still looked edible.